The present invention relates to a high-grade mastic asphalt composition, and more particularly to a high-grade mastic asphalt composition and a paving construction method using the same, where the mastic asphalt composition is of a consolute high-performance grade (PG 82-34) and enables its conveyance and paving construction with ease.
Asphalt is a refined residue from the distillation process of crude oils that involves the evaporation of volatile oil components in the crude oils. It is a chemically complicated composition consisting of hydrogen and carbon as principal components in combination with a small amount of nitrogen, sulfur and oxygen and widely used as a binder for aggregates in laying a pavement material on traffic surfaces.
As the asphalt is a thermosensitive material that undergoes a gel-to-liquid phase transition under heat and hardens at a relatively low temperature, either asphalt or aggregates or both of them are heated during the paving construction in order to promote the workability of the road pavement. As the asphalt cools over time during divided truck transports or a long-distance transport from the production facility to the paving site, or in the severe wintery weather, the asphalt concrete composition gets too hard to lay on the road and deteriorates in compactness or adhesion of aggregates with the binder materials, resulting in poor product quality of the completed pavement.
On the other hand, the mastic asphalt pavement is a double-layered composite pavement consisting of an underlying mastic asphalt having a thickness of 4 cm or less and an overlying modified asphalt having a thickness of 4 cm or greater. In this regard, the conventional mastic asphalt for the 4-cm underlying mastic asphalt adopts hard natural asphalt called “TLA (Trinidad Lake Asphalt) in combination with about 30% of general petroleum-derived asphalt. The TLA, imported all the way from foreign countries, is highly expensive and impossible to improve in terms of physical properties. Moreover, its high construction temperature of 230 to 250° C. causes deformation of the steel deck plate during the paving construction, and a lot of heat gets stuck in the pavement after the paving construction to make the pavement partly swollen, which may have an adverse effect to reduce the adhesion between the steel deck plate and the pavement and occasionally cause a break of the pavement immediately after the paving construction.
The mastic asphalt is an asphalt composition very excellent in fluidity and impervious to water due to its porosity of 1% or less, so it can be used in the concrete pavement or the waterproof pavement of the steel deck plate.
The conventional mastic asphalt, first named “Guss asphalt” and introduced to Korea, has been integrally developed into the recent mastic asphalt, which is popular in use to the waterproof layer for all the roads, including steel-deck bridges, concrete bridges, concrete pavement, side ditch, etc. to achieve recognition in its high performance.
The conventional mastic asphalt, however, necessarily requires the use of a device for mechanical agitation and conveyance, so-called “cooker” during the asphalt production and paving construction and normally takes a long time of about 1 to 2 hours for mechanical agitation and conveyance with high expense, causing inefficiency.
Furthermore, there are only a few domestic asphalt concrete companies capable of producing mastic asphalt in Korea, and many companies are mostly unable to manufacture mastic asphalt due to a lack of production facilities using high temperature of 200° C. or above (normally, 230 to 250° C.).
For this reason, the mastic asphalt is produced in a few domestic companies and transported long distances and thus faced with problems such as a rise of price, energy consumption, emission of pollutants, etc. in association with a long-distance conveyance.
According to the related prior art, KR Patent Publication No. 10-1513765 (registered on Apr. 14, 2015) under the title of “A mastic asphalt binder composition and its manufacturing method” discloses a mastic asphalt binder composition that comprises 100 pars by weight of a feed asphalt, 2 to 15 parts by weight of a polymer modifier, 4 to 15 parts by weight of a reinforcing agent, and 0 to 0.5 part by weight of a stabilizer.
According to the cited document, the mastic asphalt binder composition of the prior art exhibits excellences in rutting resistance, fatigue-cracking resistance, and constructability, and particularly in thermal stability under the temperature conditions of 230 to 250° C. and thus fits for use in the production of an impermeable asphalt mix that aims to provide waterproofing characteristics in the construction of steel-deck bridges, waterproof pavement, maintenance and repair of decrepit cement concrete, semi-rigid pavement, and so forth. But, the paving construction is performed using the mastic asphalt which is in the slurry state at high temperature of 230 to 250° C. as explained above in association with the problems with the mastic asphalt, so a lot of heat is stuck in the pavement after the paving construction to cause the swelling of the pavement and the deterioration of adhesion between the steel deck plate and the pavement, resulting in a break of the pavement immediately after the paving construction. Particularly, the mastic asphalt paving construction requires the use of a separate asphalt cooker for induction heating at high temperatures. The asphalt cooker of this type is used for special purposes only rather than general paving constructions, so it is unmarketable and requires separate equipment for mechanical agitation and conveyance, consuming a lot of time in agitation and conveyance with inefficiency.
Considering that the conventional asphalt cooker used for long-distance conveyance in the paving site is a very inefficient facility for asphalt production, the inventors of the present invention have suggested a novel composition for producing a mastic asphalt that enables the production of a mastic asphalt on site irrespective of the provision of the production facility by feeding the individual components in the paving site.
Furthermore, the current repair method for road and bridge pavement generally involves overlaying a modified asphalt of a second or third grade (PG64-22 or PG76-22).
But, the second-or-third grade asphalt pavement has a short life span and poor adhesiveness and flexibility and frequently shows segregation of ingredients and formation of portholes. Accordingly, there is a need for developing a high-grade mastic asphalt composition that has a high pavement performance (PG 82-34).